Hard surface cleaners comprising a polyurethane foam matrix and a composite of a source of silver ions and porous support material

ABSTRACT

A cleaning material for cleansing surfaces comprises a closed cell foam matrix including an antimicrobial composition. The foam matrix may be a polyurethane foam and the antimicrobial composition may comprise a source of silver ions in the form of a composite in combination with a porous support material such as titanium dioxide.

BACKGROUND OF THE INVENTION

This invention relates to the cleansing of surfaces and moreparticularly, but not exclusively, is concerned with the cleansing ofnon-absorbent hard surfaces found in the domestic environment.

It is an object of the present invention to provide a new and improvedcleaning material for cleansing a surface without scratching thesurface.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided acleaning material for cleansing surfaces which material comprises acoherent self-supporting body formed of a closed cell foam matrixincluding an antimicrobial composition which comprises a source ofsilver ions as antimicrobial agent, the composition being such thatsilver ions are released from the composition when the body is incontact with water.

In use, the surface is rubbed with the cleaning material and it isparticularly preferred for the foam matrix to be of such a friabilitythat it tends to wear away to a limited extent when being rubbed on thesurface with the ingrained dirt in the cracks and fissures in thesurface being rolled out by the fine nature of the mildly abrasiveparticles formed as the matrix crumbles in use. A rating of thefriability of the foam matrix can be found using Stable Micro SystemsLtd Texture Analyser TA-XT2 in particular in conjunction with the CraftKnife Adapter & Blades Test Unit (code A/CKB). The preferred friabilitycorresponds to a force in the range of 700-900 gms with a pre speed of2.00 mm per second using this technique.

Accordingly, another aspect of the present invention provides a methodof cleansing a surface which comprises rubbing the surface with acleaning material as above defined in the presence of water.

DETAILED DISCLOSURE

Cellular products resulting from the foaming of certain polymers aresubject to microbial attack either because the polymer is a food sourceof organisms or because the reticular form of the polymer allows thecollection of debris which serves as a food source for the organisms.The present invention utilises a closed cell foam which is unable toabsorb water and become moist. This together with the anti-bacterialcomposition means that the system is sanitary.

It is particularly preferred for the foam matrix to have a density offrom 30 to 70 (preferably from 42 to 56 kg/m3) and a substantiallyuniform and fine cell size. Preferably the foam is a rigid polyurethanefoam.

Preferably the source of the silver ions is a silver salt such as asilver halide, for example silver chloride.

In a preferred embodiment, the antimicrobial composition includes asupport material for the source of silver ions. Preferably, the supportmaterial is porous so that it can absorb the source and protect it fromambient light. Suitable support materials are oxidic materials such asparticulate titanium oxide. On contact with aqueous medium, the supportmaterial releases silver ions in a controlled way. Such supported silvercompounds are described in U.S. Pat. No. 4,906,466, the disclosure ofwhich is incorporated herein by reference.

In accordance with a particular preferred embodiment of the presentinvention, the support material is a composite comprising titaniumdioxide having an average particle size of about 1 to 15 mm, preferablyabout 2 to 5 mm, and having from about 10 to 80% preferably 20 to 60%,by weight (based on the composite) of silver chloride incorporatedtherein.

In addition to including the source of silver ions, the composition maycomprise a colourant. Suitable colourants are commercially availablecolourants such as “Solvent Yellow 98” from Hoechst or “Solvent Blue 70”from BASF. It will be understood, however, that the choice of colour isarbitrary and that any suitable colourant known in the art can be used.It is particularly preferred for the cleaning material to be colourcoded, a particular colour being used to designate the suitability ofthe material for a particular cleansing task.

The antimicrobial composition is preferably uniformly incorporated intothe foamed matrix.

Preferably the cleaning material is in the form of a block about120×50×45 mm in size and shaped to fit the hand. During use, it wearsaway to take the shape of the contours of the surface being cleaned andthis enables awkward corners to be cleaned.

When, in use, the preferred cleaning material is rubbed over the surfaceto be cleaned together with a little water (e.g. cold tap water), theclosed cell polyurethane foam wears away providing, as it does so,sufficient abrasive particles to clean dirt out of the fissures andcracks in the surface being cleaned. At the same time, silver ions areleached out of the composition to provide disinfection. As the foamedmatrix is a closed cell structure, water will only come into contactwith the silver ion source when a fresh surface is exposed due to theshearing action on the block as it is rubbed over the surface to becleaned. After cleaning, the surface is wiped over with a cloth tofinish. This removes residues created by the cleaning action but leavessufficient silver composite within the surface fissures to provide theantimicrobial action. As more water is added to the surface, so residualantimicrobial action occurs.

The cleaning material of the present invention is particularly suitablefor cleansing surfaces such as work surfaces (especially texturedmelamine surfaces), sinks (especially textured plastics sinks), alltypes of cooker hobs (particularly vitreous ceramic hobs), oveninteriors, extractor fan exterior surfaces, kitchen appliances(particularly those with textured plastic surfaces), windows andmirrors, baths and washbasins, tiles and marble, and non-absorbent floortiles.

The following Example illustrates the invention.

EXAMPLE

A free-flowing titanium dioxide/silver chloride composite powder wasprepared by reacting silver nitrate with sodium chloride in the presenceof titanium dioxide particles having an average size of from about 2 to3 mm so that, after drying, the composite contained 20% by weight silverchloride and 80% by weight titanium dioxide.

A polyurethane foam was made from a stoichiometric excess of commercialgrade diphenylmethane 4,4′-diisocyanate (MDI) and a polyol and the abovecomposite was incorporated therein. The foam was processed by dispensingit through a machine into a mould to obtain a block comprising a fineand regular closed cell foam matrix containing not more than 4% byweight of the composite and having a density in the range of from 30 to70 kg/m3.

A surface of the block was rubbed over a hard non-absorbent surface tobe cleaned in the presence of cold tap water. The block surface abradedaway slightly to form abrasive particles which effectively removed dirtfrom the fissures and cracks in the surface to be cleaned. Also, thesurface was disinfected by silver ions leached from the cells at theblock surface. During use of the block, a fresh cleaning anddisinfecting surface was continually generated as the block abradedaway. After being rubbed with the block, the cleaned surface may bewiped with a damp cloth whereby the antimicrobial action continues.

What is claimed is:
 1. A cleaning material for cleansing a non-absorbentsurface, which material comprises a coherent self-supporting body formedof a closed cell friable foam matrix into which is incorporated anantimicrobial composition which comprises a source of silver ions asantimicrobial agent, the composition being such that silver ions arereleased from the composition when the body is in contact with water,said foam matrix having a friability rating corresponding to a force inthe range of from 700 to 900 grams with a pre-speed of 2.00 mm persecond using Stable Micro Systems Texture Analyser TA-XT2 with a CraftKnife Adapter & Blade Test Unit code A/CKB.
 2. A cleaning material asclaimed in claim 1, wherein the foam matrix is a closed cellpolyurethane foam.
 3. A cleaning material as claimed in claim 2, whereinthe foam has a density of from 30 to 70 kg/m³.
 4. A cleaning material asclaimed in claim 3, wherein the foam has a density of from 42 to 56kg/m³.
 5. A cleaning material as claimed in claim 1, wherein the silverion source is present in combination with a support material.
 6. Acleaning material as claimed in claim 5, wherein the support material isa porous oxidic material.
 7. A cleaning material as claimed in claim 6,wherein the support material is particulate titanium dioxide.
 8. Acleaning material as claimed in claim 7, wherein the titanium dioxidehas an average particle size of from 1 to 15 mm.
 9. A cleaning materialas claimed in claim 8, wherein the titanium dioxide has an averageparticle size of from 2 to 5 mm.
 10. A cleaning material as claimed inclaim 1 wherein the source of silver ions is a silver salt.
 11. Acleaning material as claimed in claim 10, wherein the silver salt issilver chloride.
 12. A cleaning material for cleansing a non-absorbentsurface, which material comprises a closed cell polyurethane foam matrixinto which is incorporated a composite of silver chloride as anantimicrobial agent and particulate titanium dioxide as a supportmaterial, said foam matrix having a friability rating corresponding to aforce in the range of from 700 to 900 grams with a pre-speed of 2.00 mmper second using Stable Micro Systems Texture Analyser TA-XT2 with aCraft Knife Adapter & Blade Test Unit code A/CKB.
 13. A cleaningmaterial as claimed in claim 12 in which the silver chloride is presentin an amount of from 10 to 80% by weight based on the weight of thecomposite.
 14. A cleaning material as claimed in claim 13 wherein thetitanium dioxide has an average particle size of from 1 to 15 mm.
 15. Acleaning material as claimed in claim 14 wherein the titanium dioxidehas an average particle size of from 2 to 5 mm.
 16. A cleaning materialas claimed in claim 15 wherein the amount of silver chloride is from 20to 60% by weight based on the weight of the composite.
 17. A cleaningmaterial as claimed in claim 12 in which the composite material ispresent in an amount not exceeding 4% by weight of the closed cellpolyurethane foam.
 18. A method of cleansing a surface which comprisesrubbing, in the presence of water, the surface with a cleaning materialcomprising a coherent self-supporting body formed of a closed cellfriable foam matrix into which is incorporated a composite whichcomprises a source of silver ions as an antimicrobial agent incombination with a support material, the composition being such thatsilver ions are released from the composition which the body is incontact with water, said foam matrix having a friability ratingcorresponding to a force in the range of from 700 to 900 grams with apre-speed of 2.00 mm per second using Stable Micro Systems TextureAnalyser TA-XT2 with a Craft Knife Adapter & Blade Test Unit code A/CKB.19. A method according to claim 18 in which the closed cell friable foammatrix is polyurethane foam, the antimicrobial agent is silver chlorideand the support material is particulate titanium dioxide.